/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package com.aliyun.oss.common.utils;

import static com.aliyun.oss.common.utils.LoggerUtils.getLogger;

public class RangeSpec {
	
	private static final String RANGE_PREFIX = "bytes=";
	
	public enum Type { 
		NORMAL_RANGE, //a-b
		START_TO, //a-
		TO_END // -b
	}

	private long start;
	private long end;
	private Type type;
	
	public RangeSpec() {
		this(0, 0, Type.NORMAL_RANGE);
	}
	
	public RangeSpec(long start, long end, Type type) {
		this.start = start;
		this.end = end;
		this.type = type;
	}
	
	public long getStart() {
		return start;
	}

	public long getEnd() {
		return end;
	}

	public Type getType() {
		return type;
	}

	public static RangeSpec parse(long[] range) {
		if (range == null || range.length != 2) {
			getLogger().warn("Invalid range value " + range + ", ignore it and just get entire object");
		}
		
		long start = range[0];
		long end = range[1];
		
		if (start < 0 && end < 0 ||
				(start > 0 && end > 0 && start > end)) {
			getLogger().warn("Invalid range value [" + start + ", " + end + "], ignore it and just get entire object");
		}
		
		RangeSpec rs;
		if (start < 0) {
			rs = new RangeSpec(-1, end, Type.TO_END);
		} else if (end < 0) {
			rs = new RangeSpec(start, -1, Type.START_TO);
		} else {
			rs = new RangeSpec(start, end, Type.NORMAL_RANGE);
		}
		
		return rs;
	}
	
	@Override
	public String toString() {
		String formatted = null;
		
		switch (type) {
		case NORMAL_RANGE:
			formatted = String.format("%s%d-%d", RANGE_PREFIX, start, end);
			break;
			
		case START_TO:
			formatted = String.format("%s%d-", RANGE_PREFIX, start);
			break;
		
		case TO_END:
			formatted = String.format("%s-%d", RANGE_PREFIX, end);
			break;
		}
		
		return formatted;
	}
}
